Aviation safety investigations & reports

Boeing Co 737-33A, VH-CZX

Summary

The crew of the Boeing 737 reported that when the speed brake
was selected, during descent into Sydney with the autopilot
engaged, the aircraft rolled slightly to the right. The autopilot
was disengaged and the speed brake was again selected with the same
result. The speed brake was restowed and the flight continued and
landed without further incident.

The operator reported that inspection of the aircraft, on 15
February 2001, revealed that the left wing number three flight
spoiler "UP" cable (P/No. WSA2-3) had failed at a pulley in the
left wheel well at Wing Buttock Line (WBL) 73.00. The failure was
due to corrosion as evidenced by rust deposits at the failure
location. During rectification, all other left wing spoiler cables
were replaced due to evidence of minor corrosion. Following repair,
the aircraft was returned to service.

The operator reported that, after a previous spoiler cable
failure in 1997 due to corrosion, an Engineering Release (ER) had
been issued to require the inspection of all spoiler cables at the
next Phase 20 check and subsequent 2C check with cable replacement
at the next 4C check. Replacement at the 4C check terminated the
inspection requirements of the ER.

As a result of the cable failure on 15 February 2001, the ER was
revised to require inspection of the cables on an ongoing basis
with cable replacement at every 4C check interval to preclude
recurrence.

Subsequently, on 28 February 2001, the incident aircraft
underwent overnight maintenance at Melbourne. During the
maintenance inspection, the left wing spoiler cables, that had
previously been changed at Sydney on 15 February 2001, were found
to be mis-routed. The operator's investigation revealed that the
maintenance engineers involved in the original rectification had
travelled from Brisbane to Sydney that day and had worked a period
in excess of 24 hours with minimal breaks. Excessive hours worked
and fatigue of the maintenance engineers was considered to have
contributed to the mis-routing of the cables and the failure to
detect the mis-routing during a duplicate inspection of the spoiler
control system.

Safety Action

As a result of this ocurrence, the aircraft operator updated the
Flight Spoiler System Engineering Release to ensure the continued
integrity of B737 spoiler cables. In addition, the operator
subsequently reviewed the duty time limitations for maintenance
personnel and issued guidance material indicating that duty times
be limited to a maximum of 16 hours in any 24 hour period.

In February 2001, The Australian Transport Safety Bureau (ATSB)
released an Air Safety Information Paper titled "ATSB Survey of
Licenced Aircraft Maintenance Engineers in Australia" One of the
safety deficiencies identified during the survey was a "current
lack of programs to limit the extent of fatigue experienced by
maintenance workers". As a result of that deficiency, the ATSB
issued the following safety recommendation to the Civil Aviation
Safety Authority (CASA):

R20010033 issued February 2001

"The Australian Transport Safety Bureau recommends that
CASA ensures through hours of duty limits, or other means, that
maintenance organisations manage work schedules of staff in a
manner that reduces the likelihood of those staff suffering from
excessive levels of fatigue while on duty."

The Civil Aviation Safety Authority responded to the safety
recommendation on 31 August 2001. That response stated:

"Given that "fatigue was listed as a contributing
factor in just over 12% of occurrences", CASA believes that there
is clearly a need for the appropriate regulation of this issue.

CASA has addressed the issue of hours of duty rules and fatigue
management in relation to aircraft maintenance engineers in the
proposed Civil Aviation Safety Regulations Part 43 -Maintainers
Responsibilities and Part 145 - Approved Maintenance Organisations,
(CASR Part 43 and CASR Part 145).

Draft regulations for CASR Part 43 were released as a Discussion
Paper for public comment on 22 February 2001. A working draft of
the proposed regulations for CASR Part 145 was released for public
comment on 5 July 2001.

Proposed sub-regulation 145.190 requires an approved maintenance
organisation to ensure that each maintenance worker takes enough
rest as specified in CASR Part 43.

Proposed sub-regulation 43.400 (2) specifies the following in
relation to an appropriate work schedule for a maintenance
worker:

At least 1 period of 24 hours of complete rest away
from the workplace in any period of seven days; and

At least 10 hours of complete rest away from the workplace in
any day.

Proposed sub-regulation 43.400 (3) provides that a maintenance
worker must not continue for so long a period that the worker's
capacity to carry out the work becomes significantly impaired.

I would like to note that the Authority has recently established
a Fatigue Management Committee to review fatigue risk management
issues, fatigue standards development and implementation.

As part of this review, the Committee will be asked to review
the fatigue regulations contained in CASR Parts 43 and 145, for
consistency against CASA's fatigue management approach.

CASA anticipates that following consideration and, if
appropriate, incorporation of comments received from interested
parties, including the Fatigue Management Committee, CASR Parts 43
and Part 145 will be released as Notices of Proposed Rule Makings
for public comment later this year."